806!  '12  Kvp  -lw 
A  "AT  ' 


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...  •;  '  ';,,,'  ,,, ,   ,  ,  ,    JUN   4  )92. 

A  Study  of  the  Properties  of  Para- 

Benzyloxy  and  Para-Methoxy- 

Triphenylmethyl 


A  Contribution  to  the  Chemistry 
of  Free  Radicals 


A  DISSERTATION 


SUBMITTED  IN  PARTIAL  FULFILLMENT  OF  THE  REQUIREMENTS 

FOR  THE  DEGREE  OF  DOCTOR  OF  PHILOSOPHY 

IN  THE  UNIVERSITY  OF  MICHIGAN 


By 


Clifford  Charles  Buchlcr 


1922 


KASTON,  PA.: 

KSCHENBACH  PRINTING  COMPANV 
1922 


A  Study  of  the  Properties  of  Para 

Benzyloxy  and  Para-Methoxy- 

Triphenylmethyl 

A  Contribution  to  the  Chemistry 
of  Free  Radicals 


A  DISSERTATION 


SUBMITTED  IN  PARTIAL  FULFILLMENT  OF  THE  REQUIREMENTS 

FOR  THE  DEGREE  OF  DOCTOR  OF  PHILOSOPHY 

IN  THE  UNIVERSITY  OF  MICHIGAN 


By 

Clifford  Charles  Buchler 
J922 


EASTON,  PA.: 

ESCHENBACH  PRINTING  COMPANY 
1922 


EXCHANGE 


AC  KNOWLEDGMENT 

This  work  was  undertaken  at  the  suggestion  of  Professor  M.  Gomberg 
for  whose  constant  encouragement  and  many  helpful  suggestions,  the 
author  wishes  tc  take  this  opportunity  to  express  his  appreciation. 

CLIFFORD  CHARLKS  BUCKLER 


507582 


TABLE  OF  CONTENTS 

PAGE 

1 .  Introduction : 

Historical  Review  of  Oxygen  Containing  Triarylmethyls 7 

Object  of  This  Paper 8 

2.  Discussion  of  Results : 

Behavior  toward  Oxygen 8 

Behavior  toward  Iodine • 8 

Behavior  toward  Hydrogen  Chloride 8 

Behavior  toward  Light    9 

Formation  of  Additive  Compounds 10 

Degree  of  Dissociation , 10 

3 .  />-Benzyloxy-Triphenylmethyl : 

Preparation  of  ^-Benzyloxy-triphenyl  Carbinol 11 

^-Benzyloxy-triphenyl  Methane .  12 

^-Benzyloxy-triphenylmethyl  Chloride 12 

£-Benzyloxy-triphenylmethyl-ethyl  Ether 12 

/>-Benzyloxy-triphenylmethyl  Bromide 12 

p-Benzyloxy-triphenylmethyl 12 

Reaction  with  Oxygen 13 

Reaction  with  Iodine 13 

Reaction  with  Hydrogen  Chloride 14 

Effect  of  Light 14 

Capacity  to  Form  Additive  Compounds 14 

Degree  of  Dissociation  of  Di-£-Benzyloxy-hexaphenylethane 15 

4.  ^-Methoxy-Triphenylmethyl : 

Preparation  of  p-Methoxy-triphenyl  Carbinol 17 

^-Methoxy-triphenylmethyl  Chloride 17 

£-Methoxy-triphenylmethyl  Bromide 18 

p-Methoxy-triphenylmethyl ; 18 

Reaction  with  Oxygen 18 

Reaction  with  Iodine 19 

Reaction  with  Hydrogen  Chloride 19 

Effect  of  Light 19 

Capacity  to  Form  Additive  Compounds 20 

Degree  of  Dissociation  of  Di-£-Methoxy-hexaphenylethane 20 

5.  Summary 22 


PARA-BENZYLOXY-  AND  PARA-METHOXY-TRIPHENYLMETHYL 

1  Introduction 

Numerous  attempts  have  been  made  to  prepare,  in  the  solid  state, 
triarylmethyls  containing  oxygen  in  the  para  position  to  the  central 
carbon  atom,  but  for  the  most  part  the  results  have  proved  negative. 
All  attempts  to  isolate  the  free  radical  of  the  general  formula, 

R  \         / \ 

,^>C — <^ /OX,  in  which  R   and  R'  are  similar    or    two    different 

aromatic  nuclei,  and  X  =  H,  COCH3,  COC6H5,  CO.OC2H5,  CH3,  have 
failed,  whether  the  hydroxyl  group  was  protected  through  ester  formation 
by  the  introduction  of  an  acyl  group1  or  through  ether  formation,  by  the 
introduction  of  the  methyl  group.2  There  is  no  doubt,  however,  that  the 
respective  triarylmethyls  do  exist,  for  the  corresponding  peroxides  can 
generally  be  isolated.3  Only  one  free  radical  containing  para  oxygen, 
^-anisyl-biphenylenemethyl,4  has  been  successfully  isolated;  and  recently, 
o-methoxy-triphenylmethyl5  has  been  described. 

1  (a)  Goraberg  and  Jickling,  /.  Am.  Chem.  Soc.,  37,  2575(1915).    (b)  Gombergand 
Van  Stone,  ibid.,  38,  1577  (1916).     (c)  Gomberg  and  Johnson,  ibid.,  39,  1674  (1917). 

2  Schlenk  and  Herzenstein,  Ann.,  394,  187  (1912). 

3  Ref.  1.     Gomberg  and  West,  J.  Am.  Chem.  Soc.,  34,  1529  (1912). 

4  Schlenk  and  Mair,  Ann.,  394,  196  (1912). 

6  Gomberg  and  Nishida,  /.  Am.  Chem.  Soe.,  45,  190  (1923). 


8 

We  now  decided  to  block  the  ^-hydroxyl  group  by  a  radical  heavier 
than  the  methyl,  namely,  by  the  benzyl,  in  the  hope  that  this  would  lend 
greater  stability  to  the  free  radical  and  thereby  permit  more  readily  the 
isolation  of  such  triarylmethyls  in  the  solid  state.  This  proved  to  be  the 
case.  A  detailed  study  was  then  made  of  this  free  radical  in  respect  to  its 
behavior  toward  oxygen,  iodine,  hydrogen  chloride,  light;  its  capacity 
to  form  additive  compounds,  and  the  degree  of  dissociation  of  the  hexa- 
arylethanes. 

We  next  attempted  the  isolation  of  the  p-methoxy-triphenylmethyl, 
notwithstanding  the  negative  results  previously  obtained  in  this  Labo- 
ratory and  elsewhere,  as  mentioned  above.  The  attempt  to  isolate  this 
radical  also  was  successful. 

2  Discussion  of  Results 

Both  p-benzyloxy-  and  p-methoxy-triphenylmethyl  are  practically 
colorless,  or  light  yellow,  when  freshly  prepared,  yet  their  solutions  in 
organic  solvents  are  always  orange-yellow,  slightly  deeper  in  color  than 
those  of  triphenylmethyl.  On  exposure  to  air,  the  solutions  decolorize 
rapidly  with  the  absorption  of  the  quantity  of  oxygen  which  is  necessary 
to  form  the  corresponding  peroxides. 


I  II 

Benzene  solutions  of  the  free  radicals  absorb  iodine  rapidly,  and  the 
corresponding  triarylmethyl  iodides  result.  The  equilibrium  is  reached 
when  55  to  60%  of  the  calculated  quantity  of  iodine  has  been  added. 

The  free  radicals  in  benzene  react  with  hydrogen  chloride  with  the 
formation  of  the  corresponding  carbinol  chloride  and  the  triarylmethane 
(Equation  1),  and  these  only  partially  interact  according  to  Equation 
2,  forming  a  stable  polymer  of  the  free  radical,  that  is,  a  dialkoxy-^- 
benzhydryl-tetraphenylmethane,  (III)  : 

(CflH6W  (C.H.W  (C.H.V 

2  >C  +  HC1  =  >CC1  +  >CH  (1) 

XOC6H/  XOC6H/  XOC6H/ 

H 
(C6HB)C—  <          >—  C(C6H5)2 

(2) 


OX  OX 

III 

With  triphenylmethyl  itself  the  reaction  proceeds  largely  according  to 


9 

the  combined  scheme  in  Equations  1  and  2,  whereby  over  90%  is  trans- 
formed into  ^-benzhydryl-tetraphenylmethane,  and  only  6%  remains  as 
chloride  and  methane.  ^-Benzyloxy-  and  ^-methoxy-triphenylmethyl, 
however,  react  in  accordance  solely  with  Equation  1  to  the  extent  of  80 
to  85%;  thereby  they  resemble  diphenyl-a-naphthylmethyl,  which  forms 
chloride  and  methane6  to  the  extent  of  80%,  without  subsequent  con- 
densation of  these  two  products. 

Benzene  solutions  of  the  free  radicals  in  quartz  test-tubes,  placed  in 
direct  sunlight,  decolorize  after  several  hours'  exposure,  undergoing 
auto-oxidation  and  reduction.  In  other  words,  l/3  of  the  original  free 
radical  is  transformed  into  a  dehydrogenated  triarylmethyl,  while  2/3 
becomes  reduced  to  the  triarylmethane.  Such  a  reaction  might  proceed 
according  to  either  Equation  3  or  4. 


2(C6H6)2CH(C6H4OX)  (3) 

/*  / — \/ 

/  \ /  iv 

3(C6H6)2C(C6H4OX) 

\CX 

;C(C6H5)  +  2(C6H6)2CH(C6H4OX)  (4) 


On  exposure  to  the  air,  the  solution  absorbs  oxygen  and  forms  the  peroxide 
of  the  corresponding  biphenylene  free  radical.  This  peroxide  should 
have  the  constitution  either  VI  or  VII  according  as  to  whether  the  photo- 
chemical reaction  has  proceeded  in  the  sense  of  Equation  3  or  of 
Equation  4. 


/         \C— C«H4OX  /  Nc— C6H5 

V*JTX  I  XC6H3OX/  | 

O  O 

VI  I      VII 

O 


/V^6 

C          >C— C6H4OX  <  >C— CeH5 

\C6H/ 

The  peroxide  VI,  where  X  =  CH3,  was  synthesized  according  to  Schlenk 
and  Mair,7  and  it  proved  different  from  the  peroxide  actually  ob tamed 
in  our  photochemical  reaction.  The  peroxide  of  the  constitution  VII 
was  then  synthesized  as  follows.  3-Methoxy-9-fluorenone  (VIII)  was 
made  according  to  Ullmann  and  Bleir8  from  anthranilic  acid.  The  car- 
binol  (IX),  prepared  through  the  Grignard  reaction,  was  then  converted 

6  Gomberg  and  Schoepfle,  7.  Am.  Chem.  Soc.,  41,  1663  (1919). 

7  Ref.  4,  p.  198. 

8  Ullmann  and  Bleir,  Ber.,  35,  4273  (1902). 


10 


into  the  chloride  in  the  usual  manner.  Exposure  to  the  air  of  a  solution 
of  the  chloride  previously  shaken  with  molecular  silver  gave  a  peroxide, 
the  constitution  of  which  could  be  no  other  than  XI.  It  proved  identical 
with  the  peroxide  obtained  from  the  ^-methoxy-triphenylmethyl  by 
action  of  light  and  subsequent  oxidation. 

VIII  IX 


Carbinol 
chloride 


C6H 


^-Benzyloxy-  and  £-methoxy-triphenylmethyl  were  crystallized  from 
a  large  number  of  solvents  representing  esters,  ethers,  ketones,  and  hydro- 
carbons, but  in  only  one  case  was  an  additive  compound  formed,  namely,  be- 

tween ether  and  £-benzyl- 


60 


55 


50 


45 


40 


Dissociation  of 
U/-p-ben  zylcxxij-hexaphenLj!  Ethane 


CeHA  53' 


oxy-triphenylmethyl,     and 
here   only  partially.      The 
isolated  free  radical  never 
contained  over  50%  of  the 
additive  compound.     This 
negative  behavior  is  quite 
in  contrast  to  that  of  tri- 
phenylmethyl,  which  forms 
additive  compounds  readily 
with  all  classes  of  solvents/ 
It  furnishes  further  experi- 
mental evidence  in  support 
of  the  hypothesis9  which  at- 
tempts to  relate  capacity  of 
the     hexa-arylethanes      to 
form   additive    compounds 
and  their  degree  of  dissocia- 
tion into  free  triarylmethyls. 
The  degrees  of  dissocia- 
tion of  the   two   dialkoxy- 
hexa-arylethanes,  that  is,  the  molecular  weight  of  the  ^-benzyloxy-  and  p- 
methoxy  free  radicals,  were  carefully  determined  in  a  number  of  solvents 
over  a  wide  range  of  temperature  and  concentration.     The  molecular  state 
•  Ref.  6,  p.  1672. 


§ 
I 


"} 

"7 

Q 


O  concentration  in  Percent. 


9.6' 
QCzHiBr  -17 

\ 

C6H6     4.9{ 


0 


Fig.  1. 


11 


Dissociation  of 
DiTp-methoxLj-hexaphenijI  Ethane. 


of  the  triarylmethyls  is  undoubtedly  best  represented  by  the  formulation 
which  involves  simultaneously  both  dissociation  of  the  hexa-artylethane  and 
subsequent  tautomerization  of  the- triarylmethyl  to  the  quinonoid  state.10 
However,  since  the  question  of  tautomerism  is  not  involved  in  the  dis- 
cussion in  this  paper,  the  dissociation  of  di-£-benzyloxy-  and  di-£-methoxy- 
hexaphenylethane  into  the  corresponding  triarylmethyls  may  be  formu- 
lated for  this  discussion  by  the  simple  system:  R3C — CR3^I^2  R3C. 

As  was  to  be  expected,  this  equilibrium  was  influenced  by  the  concen- 
tration of  the  solute,  the  temperature  and  nature  of.  the  solvent.  The 
degree  of  dissociation  was 
found  to  decrease  with  in- 
crease in  concentration,  and 
increase  with  temperature, 
while  the  nature  of  the  sol- 
vent also  seemed  to  exert 
an  influence.  (Figs.  1  and 
2.)  With  di-^-benzyloxy- 
hexaphenyl  ethane  at  the 
freezing  point  of  benzene 
for  a  2%  concentration,  the 
equilibrium  is  reached  be-  ^ 
tween  36%  of  the  triaryl- 
methyl  and  64%  of  the  £0 
ethane;  while  for  di-p-  a 

methoxy-hexaphenylethane 

under  the  same  conditions  the  equilibrium  is  between  25%  of  the  triaryl- 
methyl  and  75%  of  the  ethane.  Thus,  these  2  free  radicals  exist  to  a  much 
greater  extent  in  the  monomolecular  form  than  does  hexaphenylethane, 
which  is  dissociated  to  the  extent  of  2  to  5%  under  these  conditions.  It 
would  seem  that  the  heavier  benzyl  group  induces  greater  dissociation  tend- 
ency than  the  lighter  methyl  group.  As  regards  the  relative  influence  of 
the  orientation,  the  methoxy  group  in  either  ortho*  or  para  position  exerts 
about  the  same  influence. 

Experimental 

3  ^-Benzyloxy-triphenylmethyl 
^-Benzyloxy-triphenyl     Carbinol, 


40 


30 


Concentration  in  Percent. 


53° 

C2H4Br2     9.6° 

ClCaH4Br-l7' 

CeHe   46' 


.— The    £-hydroxy- 

triphenyl  carbinol  was  prepared  by  the  condensation  of  benzophenone  chloride  and 
phenol;11  40  g.  (1  mole)  of  />-hydroxy-triphenyl  carbinol  was  dissolved  in  a  solution 
containing  14  g.  (2.4  mole)  of  sodium  hydroxide  in  150  cc.  of  water  in  a  flask  provided 
with  a  reflux  condenser  and  an  efficient  stirrer.  To  this  was  added  22  g.  (1.2  mole) 
of  benzyl  chloride  and  the  reaction  mixture  was  heated  for  4  hours  in  an  oil-bath  at  50°, 


10  Gomberg  and  Sullivan,  J.  Am.  Chem.  Soc.,  44,  1811,  1832  (1922). 

11  Gomberg  and  Jickling,  ibid.,  38,  3578  (1915). 


12 

with  rapid  stirring.  After  it  had  cooled,  the  alkaline  supernatant  liquid  was  decanted, 
and  the  solid  product  digested  with  warm  5%  alkali  solution,  in  order  to  remove  any 
unchanged  £-hydroxy-triphenyl  carbinol.  After  the  product  had  been  filtered  and 
washed  thoroughly  with  water  it  was,  while  still  moist,  digested  with  25  cc.  of  alcohol 
to  remove  any  occluded  benzyl  alcohol  or  chloride.  By  following  this  procedure,  yields 
of  90%  were  obtained.  After  several  recrystallizations  from  benzene,  £-benzyloxy- 
triphenyl  carbinol  was  obtained  in  pure  white  crystals;  m.  p.,  94°. 

Analyses.     Calc.  for  C26H22O2:   C,  85.34;  H,  6.01.     Found:   C,  85.34;  H,  5.97. 

£-Benzyloxy-triphenylmethane. — Ten  g.  of  the  carbinol  was  dissolved  in  50  cc.  of 
glacial  acetic  acid  and,  after  the  addition  of  15  g.  of  zinc  dust,  the  solution  was  gently 
boiled  under  a  reflux  condenser  until  it  became  colorless.  While  the  mixture  cooled, 
£-benzyloxy-triphenylmethane  crystallized,  the  yield  being  practically  quantitative. 
Upon  recrystallization  from  alcohol  the  substance  separated  hi  white  needles  which 
melted  at  116.5°. 

Analyses.     Calc.  for  C26H22O:   C,  89.14;  H,  6.28.     Found:   C,  89.26;  H,  6.31. 

£-Benzyloxy-triphenylmethyl  Chloride,  (C7H7OC6H4).(C6H5)2CC1.— The  chloride 
was  prepared  by  saturating  a  benzene  solution  of  the  carbinol  with  dry  hydrogen 
chloride  in  the  presence  of  anhydrous  calcium  chloride.  After  the  solution  had  stood 
overnight  and  become  concentrated,  the  chloride  crystallized.  For  all  further  work 
the  chloride  was  always  recrystallized  from  absolute  ether;  m.  p.,  77°. 

Analysis.     Calc.  for  C^H^OCl:    Cl,  9.22.     Found:    9.20. 

Upon  addition  of  the  theoretical  quantities  of  ferric  chloride,  zinc  chloride,  mercuric 
chloride,  or  stannic  chloride  in  ethyl  acetate,  to  a  benzene  solution  of  the  triarylmethyl 
chloride,  the  corresponding  red  double  salts  immediately  separated  as  an  oil.  Later 
these  salts  became  crystalline,  with  the  exception  of  the  zinc  salt. 

Analyses.  Calc.  for  C26H21OCl.FeCl3:  Cl,  25.94.  Found:  26.20.  Calc.  for 
C26H21OCl.SnCl4:  Cl,  27.49.  Found:  27.92. 

£-Benzyloxy-triphenylmethyl-ethyl  Ether,  (C7H7OC6H4) .  (C6H6)2COC2H5.— This 
ether  was  prepared  by  the  addition  of  benzyloxy-triphenylmethyl  chloride  to  a  solution 
of  sodium  ethylate.  On  crystallization  from  alcohol  it  separated  in  fine  needles;  m.  p., 
89°.  ;; 

^Benzyloxy-triphenylmethyl  Bromide,  (C7H7OC6H4).(C6H5)2CBr. — In  order  to 
prepare  the  bromide,  slightly  more  than  the  calculated  amount  of  acetyl  bromide  was 
added  to  the  carbinol  dissolved  in  benzene.  The  solution  was  warmed,  and  after  con- 
centration and  the  addition  of  petroleum  ether  to  it,  the  bromide  crystallized.  From 
absolute  ether  the  bromide  crystallizes  in  white  needles  which  melt  at  90°. 

Analysis.     Calc.  for  C26H21OBr:    Br,  18.63.     Found:    18.58. 

Preparation  of  ^-Benzyloxy-triphenylmethyl. — Three  g.  of  benzyloxy-triphenyl- 
methyl chloride  together  with  3  g.  of  molecular  silver  was  introduced  into  a  glass  tube  of 
30  cc.  capacity,  the  latter  completely  filled  with  dry  thiophene-free  benzene,  and  quickly 
stoppered,  so  as  to  be  absolutely  air-tight.  After  having  been  shaken  for  8  hours,  the 
solution  of  the  free  radical  was  siphoned  into  the  apparatus  especially  designed  for  work 
with  free  radicals,  and  described  in  previous  papers.  The  apparatus  was  immersed 
in  a  jar  of  warm  water,  at  45-50°,  and  the  benzene  removed  under  reduced  pressure; 
then  10  cc.  of  warm  acetone  was  added  to  dissolve  the  oily  residue.  The  apparatus, 
filled  with  carbon  dioxide  under  slight  pressure,  was  allowed  to  remain  in  a  cool  place 
overnight,  whereupon  ^-benzyloxy-triphenylmethyl  crystallized.  The  supernatant 
liquid  was  drawn  off,  and  after  the  substance  had  been  washed  several  times  with  acetone, 
it  was  thoroughly  dried  in  a  slow  stream  of  dry  carbon  dioxide  under  reduced  pressure. 
Of  the  different  solvents,  acetone,  ether,  ethyl  acetate,  carbon  disulfide,  and  methylethvl 


13 

ketone,  the  first  was  found  to  be  the  most  suitable,  giving  the  purest  product  and  the 
best  yield,  usually  about  1.5  g.  In  an  atmosphere  of  carbon  dioxide  the  free  radical 
begins  to  darken  at  about  125°  and  melttf-at  142-145°. 

Analyses.  Calc.  for  C26H2iO:  C,  89.40;  H,  6.02.  Found:  C,  89.33,  89.50;  H, 
6.36,  6.15. 

Reaction  of  ^-Benzyloxy-triphenylmethyl  with  Oxygen. — Although 
^-benzyloxy-triphenylmethyl  when  perfectly  dry  may  be  exposed  to  the 
air  for  short  periods  of  time  without  harm,  it  is  much  more 
susceptible  to  oxidation  than  is  triphenylmethyl.  Its  solutions  on  ex- 
posure to  the  air  decolorize  rapidly  with  the  absorption  of  oxygen,  and  this 
reaction  may  be  used  as  a  check  on  the  purity  of  samples  of  the  free  radi- 
cal. The  absorption  is  very  rapid,  reaching  the  limit  in  less  than  5  min- 
utes. In  the  following  table  are  given  the  results  of  some  typical  experi- 
ments on  the  absorption  of  oxygen  based  on  weighed  samples  of  the 
crystalline  free  radical  in  bromobenzene  as  a  solvent,  and  also  on  the  free 
radical  in  solution  prepared  directly  from  a  definite  quantity  of  the  chlor- 
ide.12 

TABLE  I 

ABSORPTION  OF  OXYGEN  BY  BENZYIVOXY-TRIPHENYLMETHYI, 
Wt.  of  Sample  Oxygen  Absorbed 

•     Chloride  Free  radical 

G  G.  Cc.  (N.  T.  P.)  %  of  calc. 

1  ....  29.43  101.0 

1  ....  28.90  99.2 

1  29.03  99.7 

1.0302  33.52  101.4 

1.2800  41.53  101.1 

Although  practically  the  calculated  quantity  of  oxygen  is  absorbed, 
yet  the  amount  of  peroxide  isolated  from  the  reaction  is  usually  only 
about  90%. 

In  order  to  determine  the  yield  of  peroxide,  a  weighed  sample  of  the  free  radical 
was  dissolved  in  benzene  and  the  solution  exposed  to  the  air.  After  the  benzene  was 
allowed  to  evaporate,  the  residue  was  rubbed  up  several  times  with  ether;  the  peroxide 
was  then  transferred  to  a  weighed  alundum  crucible  and  thoroughly  washed  with  ether; 
1.432  g.  of  radical  gave  1.352  g.  of  peroxide,  which  is  90.3%  of  the  calculated  amount. 
In  two  other  experiments,  yields  of  91.2  and  90.8%  were  obtained.  This  is  the  largest 
yield  obtained  from  any  triarylmethyl  so  far  reported.  When  the  peroxide  was  re- 
crystallized  from  hot  benzene  to  which  an  equal  amount  of  ether  had  been  added,  it  was 
obtained  in  fine  white  crystals;  m.  p.,  171  °. 

Analyses.  Calc.  for  CnH^O*:  C,  85.48;  H,  5.75.  Found:  C,  85.52;  H,  5.89. 
Reaction  of  ^-Benzyloxy-triphenylmethyl  with  Iodine. — The  amount 
of  iodine  that  is  absorbed  by  benzyloxy-triphenylmethyl  was  determined 
by  titrating  weighed  samples,  in  absence  of  air,  with  a  standard  O.I  N 
solution  of  iodine  in  benzene,  the  end-point  being  indicated  by  the  first 
change  in  color  due  to  excess  of  iodine.  The  equilibrium  is  reached  when 

»  Ref.  10,  p.  1816. 


14 

approximately  60%  of  the  calculated  amount  of  iodine  has  been  added; 
1.351  g.  required  23.0  cc.  of  0.1  N  iodine,  which  is  59.5%  of  the  calculated 
amount.  In  two  other  experiments,  54.4  and  59.1%  were  obtained. 

^-Benzyloxy-triphenylmethyl  iodide  was  not  isolated  from  the  above  reac- 
tion mixture.  The  iodide  is  very  unstable  and  a  benzene  solution  of  it  on  ex- 
posure to  the  air  immediately  darkens,  due  to  the  liberation  of  free  iodine. 
However,  the  presence  of  the  iodide  was  proved  by  converting  it  into  the 
anilide,  and  this  proved  identical  with  the  compound  obtained  by  the 
action  of  aniline  directly  upon  the  carbinol  chloride. 

Action  of  Hydrogen  Chloride  on  ^-Benzyloxy-triphenylmethyl.—  A 
benzene  solution  of  the  free  radical  was  treated  with  20  cc.  of  benzene 
saturated  with  hydrogen  chloride.  After  several  hours  the  orange  color 
of  the  solution  of  the  free  radical  had  gradually  changed  to  reddish-yellow. 
The  solution  then  failed  to  absorb  oxygen. 

In  order  to  determine  the  extent  to  which  the  reaction  proceeds  accord- 
ing to  Equation  1,  the  amount  of  ^-benzyloxy-triphenylmethyl  chloride 
was  determined.  The  benzene  solution  containing  a  weighed  sample  of 
the  free  radical,  after  having  been  subjected  to  the  action  of  hydrogen 
chloride,  was  concentrated  under  reduced  pressure,  in  order  to  remove 
the  excess  of  hydrogen  chloride.  To  insure  complete  removal  of  the  latter, 
the  residue  was  again  taken  up  in  benzene  and  concentrated.  From  the 
chlorine  content  of  the  residue,  the  amount  of  £-benzyloxy-triphenyl- 
methyl  chloride  was  calculated;  2.019  g.  of  the  radical  gave  0.971  g.  of 
the  chloride,  which  is  equivalent  to  87.3%  of  the  calculated  amount, 
while  another  sample  of  1.920  g.  of  the  radical  gave  0.976  g.  of  the  chloride, 
which  is  92.2%  of  the  calculated  amount. 

Effect  of  Light  on  ^-Benzyloxy-triphenylmethyl. — A  benzene  solution 
of  the  free  radical  was  exposed  in  a  quartz  test-tube  to  the  direct  sunlight ; 
the  color  of  the  free  radical  disappeared  after  several  hours.  On  exposure 
to  the  air,  the  solution,  which  then  contained  a  biphenylene  free  radical 
and  ^-benzyloxy-triphenylmethane  (See  Equation  4)  absorbed  oxygen  in 
practically  the  calculated  amount  for  the  formation  of  the  corresponding 
peroxide.  Although  the  latter  was  not  isolated  in  the  pure  state,  the 
methane  was  isolated  and  identified  as  such. 

Formation  of  Additive  Compounds  of  £-Benzyloxy-triphenylmethyl.— 
In  order  to  determine  whether  ^-benzyloxy-triphenylmethyl  possesses  the 
property  of  forming  additive  compounds  with  different  classes  of  solvents, 
the  free  radical  was  made  as  previously  described,  and  for  acetone  were 
substituted  the  following  solvents:  Ethers:  ethyl  ether,  iso-amylzthyl 
ether,  butylmethyl  ether,  butylethyl  ether;  Ketones:  methyl-ethyl 
ketone,  diethyl  ketone;  Esters:  ethyl  acetate,  propyl  acetate,  propyl 
butyrate;  Hydrocarbons:  benzene,  toluene,  xylene;  Acetonitrile;  Carbon 
.disulfide.  The  supernatant  liquid  was  drawn  off  and  the  free  radical 


15 

thoroughly  washed,  first  with  mixtures  of  the  respective  solvent  and  petro- 
leum ether,  b.  p.  50-60°,  and  finally  with  pure  petroleum  ether  in  order 
to  insure  complete  removal  of  all  adhering  solvent.  The  free  radical  was 
transferred  to  a  porcelain  boat,  weighed,  and  placed  in  a  tube  through 
which  a  slow  stream  of  dry  carbon  dioxide  was  passed  under  reduced  pres- 
sure. The  tube  was  heated  in  an  air-bath  at  50-55°  for  1  hour,  and  after 
the  boat  had  cooled  to  room  temperature  it  was  reweighed. 

With  only  one  solvent,  absolute  ether,  did  the  free  radical  combine,  and 
always  with  less  than  required  for  2  moles  of  triarylmethyl  to  1  of  ether. 
With  3  separate  samples  of  about  1.5  g.  each  the  loss  was  4.03,  4.06, 
and  3.52%,  respectively,  against  the  calculated  9.60%. 

Degree  of  Dissociation  of  Di-^-benzyloxy-hexaphenyle thane. — For 
the  determination  of  the  molecular  weight  of  ^-benzyloxy-triphenyl- 
methyl,  the  usual  standard  Beckmann  apparatus  was  employed.  The 
freezing-point  tube  was  fitted  with  a  rubber  stopper,  through  which 
passed  a  small  glass  inlet  tube  for  hydrogen,  and  a  Beckmann  thermometer. 
The  side-arm  was  fitted  with  a  rubber  stopper  through  which  passed  an 
outlet  tube  for  hydrogen,  a  glass  tube  in  which  the  pellets  were  weighed, 
and  a  nickel  wire  flattened  at  one  end  so  as  to  cover  completely  the  outlet 
of  the  pellet-tube,  thus  protecting  the  pellets  from  the  vapor  of  the  solvent, 
for  otherwise  they  became  gummy.  The  apparatus  was  provided  with  a 
2 -ring  electromagnetic  stirrer. 

In  the  earlier  part  of  this  investigation  the  free  radical  was  crystallized 
from  absolute  ether  and,  in  order  to  remove  the  ether,  the  substance  was 
heated  for  1  hour  at  50-55°  in  a  slow  stream  of  dry  carbon  dioxide  under 
reduced  pressure.  Even  then  the  material  apparently  still  retained  some 
solvent,  which  made  it  impossible  to  obtain  uniform  product.  It  was, 
therefore,  found  necessary  to  use  acetone  as  the  solvent  for  the  crystalliza- 
tion instead  of  ether.  The  substance  was  dried  for  1  hour  in  a  stream  of 
carbon  dioxide  under  reduced  pressure,  quickly  powdered  and  made  into 
pellets.  The  pellets  were  then  weighed  in  the  small  glass  tube  and  the 
apparatus  assembled  containing  a  weighed  quantity  of  solvent. 

For  temperatures  below  0  °,  a  Dewar  flask  was  used  which  was  filled  with 
ether  and  was  connected  to  a  suction  pump.  By  the  careful  adjustment  of 
the  vacuum  the  bath  could  be  maintained  at  a  constant  temperature 
within  a  degree,  as  shown  by  the  thermometer  in  the  ether. 

In  all,  6  solvents  were  used,  ranging  in  temperature  from  — 17°  to  +53°; 
all  were  very  carefully  purified  by  repeated  distillation,  and  the 
^-dichlorobenzene  in  addition  was  recrystallized  from  alcohol.  Usually 
the  material  was  added  in  4  lots,  giving  concentrations  ranging  from 
1  to  5%  Each  set  of  determinations  represents  a  separate  prep- 
aration, the  free  radical  having  been  allowed  to  crystallize  over  night  and 
used  the  next  day. 


16 

The  constant  K  was  determined  for  each  individual  solvent  under 
exactly  the  same  conditions  as  prevailed  in  the  molecular-weight  deter- 
minations of  the  free  radical,  using  triphenylmethane  which  had  been 
very  carefully  purified  by  several  vacuum  distillations  and  recrystalliza- 
tions.  The  quantity  of  free  radical  (Col.  2)  is  taken  as  hexa-arylethane 
in  calculating  the  molecular  weight  and  the  degree  of  dissociation. 


II 
MOLECULAR  WEIGHT  OF  DI-PARA-BENZYLOXY-HEXAPHENYLETHANE 


Solvent                     Solute                 Cone. 

Depression 

Mol. 

Dissociat 

G 

G.                       % 

0  C. 

wt. 

% 

SOLVENT:  ETHYLENE  CHLOROBROMIDE,  F.  p., 

—17°    E 

>83.4 

24. 

70               0.3224            1.30 

0.231 

471.3 

48.1 

0.8181            2.50 

0.422 

494.6 

41.1 

0.9487            3.84 

0.610 

525.1 

32.9 

1.2222            4.95 

0.760 

543.0 

28.5 

35. 

29               0.3455            1.36 

0.338 

478.7 

45.8 

0.6458            2.55 

0.434 

490.7 

42.2 

0.9433            3.73 

0.600 

518.5 

34.6 

1.2510            4.94 

0.772 

534.4 

30.6 

SOLVENT:  BENZENE,  F 

.p.,  4.9°    t 

:  =  52.0 

20. 

98               0.2753            1.31 

0.138 

494.4 

41.2 

0.4852            2.31 

0.232 

518.4 

34.6 

0.6949            3.31 

0.321 

536.5 

30.1 

0.9513            4.53 

0.428 

550.9 

26.7 

21. 

15               0.2472            1.17 

0.124 

490.2 

42.4 

0.4381            2.07 

0.207 

515.4 

35.4 

0.6321            2.99 

0.396 

525.0 

32.9 

0.8970            4.24 

0.405 

544.5 

28.2 

SOLVENT:  NITROBENZENE, 

F.  p.,  5.8° 

#=71.2 

19. 

94               0.2234            1.12 

0.155 

514.6 

35.6 

0.4397            2.20 

0.299 

525.1 

32.9 

0.6212            3.11 

0.409 

542.3 

28.7 

0.8764            4.39 

0.570 

549.0 

27.1 

20. 

12               0.2074            1.03 

0.144 

509.7 

36.9 

0.4388            2.18 

0.299 

519.3 

34.4 

0.6528            3.24 

0.423 

546.1 

27.8 

0.8890            4.42 

0.568 

553.9 

26.0 

SOLVENT:  ETHYLENE  DIBROMIDE,  F.  p.,  9.6°    #  =  114.9 
26.04 


25.94 


0.3541 

1.36 

0.327 

477.8 

46.1 

0.6467 

2.48 

0.595 

479.6 

45.5 

0.9874 

3.79 

0.867 

502.5 

38.9 

1.2934 

4.97 

1.118 

510.5 

36.7 

0.3347 

1.29 

0.315 

470.7 

48.3 

0.6630 

2.55 

0.607 

483.8 

44.2 

1.0223 

3.94 

0.904 

500.9 

39.3 

1.3000 

5.01 

1.139 

505.6 

38.0 

17 

SOLVENT  :  £-BROMOTOLUENE,  F.  p. ,  27  °    K  =  83 .9 

25.24  0.2957  1.17  0.197  498.9  39.9 

0.6077  2.41  0.390  518.0  34.7 

0.9270  3.67''  0.570  540.6  29.1 

1.2253  4.85  0.715  569.6  22.5 

24.22  0.3251  1.34  0.224  503.8  38.8 

0.6432  2.65  0.424  525.5  32.8 

0.9676  3.99  0.607  552.2  26.4 

1.2499  5.16  0.779  555.8  25.6 

SOLVENT:  P-DICHLOROBENZENE,  F.  p.,  53°    K  —  75A 

25.61               0.3498  1.36  0.230  447.8  55.9 

0.6467  2.52  0.420  453.3  54.0 

0.9518  3.72  0.605  463.2  50.7 

1.2853  5.02  0.801  472.4  47.7 

26.24               0.3217  1.22  0.210  440.2  58.5 

0.6432  2.45  0.403  458.6  52.2 

0.9182  3.50  0.569  463.7  50.5 

1.1871  4.52  0.730  467.3  49.3 

4  ^-Methoxy-triphenylmethyl 

£-Methoxy-triphenyl  Carbinol,  (CHsO.CeHO.CCeHs^COH. — This  carbinol  has 
previously  been  prepared  by  the  action  of  phenylmagnesium  bromide  upon  the  methyl 
ester  of  ^-anisic  acid13  and  also  by  heating  ^-hydroxy-triphenyl  carbinol  with  methyl 
iodide  in  the  presence  of  sodium  hydroxide  in  sealed  tubes,  using  alcohol  as  a  solvent.14 
However,  a  superior  method,  both  with  respect  to  yields  and  cheapness  of  materials, 
is  that  based  on  the  action  of  dimethyl  sulfate  on  an  alkaline  solution  of  ^-hydroxy- 
triphenyl  carbinol.  To  10  g.  (1.6  mole)  of  sodium  hydroxide  dissolved  in  160  cc  of  water 
was  added  44  g.  (1  mole)  of  />-hydroxy-triphenyl  carbinol,  and  the  mixture  was  warmed 
until  a  clear  solution  was  obtained;  26.5  g.  (1.3  mole)  of  dimethyl  sulfate  was  added 
through  a  dropping  funnel  during  the  course  of  an  hour,  while  the  reaction  mixture  was 
constantly  stirred  and  the  stirring  continued  until  the  product  which  separated  had 
solidified.  The  benzene  solution  of  the  methylated  product  was  stirred  with  5% 
sodium  hydroxide  solution  to  remove  any  occluded  hydroxy-triphenyl  carbinol  and, 
after  several  washings  with  water,  was  dried  over  calcium  chloride.  The  benzene  was 
completely  removed  under  reduced  pressure,  the  viscous  residue  dissolved  in  10  cc. 
of  dry  ether,  and  enough  petroleum  ether  added  to  cause  turbidity.  When  the  solution 
was  seeded,  pure  ^-methoxy-triphenyl  carbinol  separated  out,  the  yields  ranging  from 
80  to  85%.  After  one  recrystallization  from  equal  parts  of  dry  ether  and  petroleum 
ether  (80-100°)  the  carbinol  was  obtained  in  white  crystals  which  melted  at  82°. 

Analyses.     Calc.  for  C20H]8O2:   C,  82.76;  H,  6.21.     Found:   C,  82.70;  H,  6.30. 

/>-Methoxy-triphenylmethyl  Chloride,  (CHsOCsKUMCal^CCl.16— An  ethereal 
solution  of  the  carbinol  was  warmed  with  2  to  3  times  the  calculated  quantity  of  acetyl 
chloride;  as  the  solution  cooled,  methoxy-triphenylmethyl  chloride  crystallized  prac- 
tically quantitatively.  When  the  chloride  was  washed  thoroughly  upon  the  filter  with 
ether  and  petroleum  ether,  and  dried  in  a  vacuum  desiccator  over  sodalime,  it  melted 
at  122°  and  needed  no  further  recrystallization.  It  may,  however,  be  readily  recrystal- 
lized  from  dry  ether,  in  which  it  is  quite  insoluble  in  the  cold. 

13  Baeyer  and  Villiger,  Ber.,  35,  3027  (1902). 

14  Bistrzycki  and  Herbst,  ibid.,  36,  2334  (1903). 

15  Ref.  14,  p.  2335.     Baeyer  and  Villiger,  ibid.,  36,  2789  (1903). 


18 

Analysis.     Calc.  for  C20H17OC1:   Cl,  1150.     Found:   11.42. 

Methoxy-triphenylmethyl  chloride  gives  crystalline  red  double  salts  with  ferric 
chloride,  zinc  chloride,  mercuric  chloride  or  stannic  chloride. 

Analyses.  Calc.  for  C2oH17OCl.FeCl3:  Cl,  30.13.  Found:  30.65.  Calc.  for 
C20Hi7OCl.ZnCl2:  Cl,  23.90.  Found:  23.94. 

p-Methoxy-triphenylmethyl  Bromide. — The  bromide  was  prepared  by  exactly  the 
same  procedure  as  that  used  for  the  chloride,  with  the  substitution  of  acetyl  bromide  for 
chloride.  The  bromide  is  best  recrystallized  from  absolute  ether;  m.  p.,  143 °. 

Analysis.     Calc.  for  C20Hi7OBr:  Br,  22.64.     Found:  22.87. 

Preparation  of  ^-Methoxy-triphenylmethyl. — The  procedure  used  for  the  preparation 
of.  />-benzyloxy-triphenylmethyl  served  also  for  the  preparation  of  this  free  radical; 
4  g.  of  />-methoxy-triphenylmethyl  chloride  (in  benzene)  and  4  g.  of  molecular  silver 
were  shaken  together  for  6  hours.  The  orange-colored  solution  of  the  free  radical  was 
transferred  to  the  usual  form  of  apparatus  and  the  benzene  completely  removed  at  50- 
55°.  The  oily  residue  of  the  crude  material,  left  upon  evaporation  of  the  benzene,  was 
dissolved  in  5  cc.  of  warm  absolute  ether,  and  the  free  radical  allowed  to  crystallize. 
Four  g.  of  the  chloride  usually  gave  about  2  g.  of  />-methoxy-triphenylmethyl.  In  an 
atmosphere  of  carbon  dioxide,  the  substance  begins  to  darken  at  125°  and  melts  at 
145-150°,  but  not  sharply.  The  free  radical  may  also  be  crystallized  from  acetone,  in 
which  it  is  slightly  more  soluble  than  in  ether. 

Analyses.  Calc.  for  C20HI7O:  C,  87.92;  H,  6.23.  Found:  C,  88.14;  H,  6.29. 
Reaction  of  ^-Methoxy-triphenylmethyl  with  Oxygen. — The  free 
radical  when  perfectly  dry  may  be  exposed  to  the  air  without  suffering  appre- 
ciable oxidation.  Its  solutions,  however,  on  exposure  to  the  air  decolorize 
rapidly,  with  the  formation  of  the  peroxide.  The  amount  of  oxygen 
which  is  taken  up  was  measured  quantitatively,  using  the  same  procedure 
as  described  for  benzyloxy-triphenylmethyl. 

TABLE  III 

ABSORPTION  OF  OXYGEN  BY  METHOXY-TRIPHENYLMETHYL 
Wt.  of  Sample  Oxygen  Absorbed 

Chloride  Free  radical 

G.  G.  Cc.  (N.  T.  P.  %  of  calc. 

1  36.67  101.0 

1  36.85  101.5 

1  ....  36.57  100.8 

1  ....  36.58  100.8 

0.8000  33.04  100.6 

1.1574  48.08  101.2 

Although  the  quantity  of  oxygen  absorbed  is  very  nearly  that  calculated 
yet  the  amount  of  crystalline  peroxide  is,  as  in  all  other  instances,  less 
than  this.  With  four  separate  samples  of  from  1  to  1.3  g.  of  the  free 
radical,  the  yields  were  from  79.2  to  82.0%  of  the  calculated  amount. 

The  peroxide  is  quite  soluble  in  benzene,  chloroform  or  carbon  tetrachloride,  and 
practically  insoluble  in  ether  or  petroleum  ether.  It  can  best  be  recrystallized  by 
solution  in  hot  benzene  and  the  addition  of  an  equal  volume  of  ether.  It  crystallizes 
in  fine  white  crystals;  m.  p.,  157°. 

Analyses.     Calc.  for  C^Hs^:   C,  83.05;  H,  5.88.     Found:   C,  83.36;  H,  6.02. 


19 

Reaction  of  ^-Methoxy-triphenylmethyl  with  Iodine. — The  quantity 
of  iodine  absorbed  was  determined  as  described  under  benzyloxy-triphenyl- 
methyl.  The  equilibrium  was  established  when  about  58%  of  the  calcu- 
lated quantity  of  iodine  had  been  added.  With  three  separate  samples 
the  yields  were  from  57  to  59.7%. 

The  presence  of  ^-methoxy-triphenylmethyl  iodide  was  proved  by  the 
formation  of  methoxy-triphenylmethyl  anilide  upon  the  addition  of  aniline 
to  the  above  solution.  The  anilide  was  identical  with  that  formed  from 
the  carbinol  chloride  and  aniline  according  to  Baeyer  and  Villiger.16 

Action  of  Hydrogen  Chloride  on  ^-Methoxy-triphenylmethyl. — As  in 
the  case  of  benzyloxy-triphenylmethyl,  when  hydrogen  chloride  is  allowed 
to  react  on  a  benzene  solution  of  the  free  radical,  the  color  disappears  and 
the  solution  then  fails  to  absorb  oxygen.  The  amount  of  chloride  formed 
according  to  Equation  4  was  determined  as  previously  described,  and  was 
found  to  be,  with  2  separate  samples,  80.5  and  88.9%,  respectively. 

Effect  of  Light  on  ^-Methoxy-triphenylmethyl. — A  benzene  solution 
exposed  to  direct  sunlight  became  decolorized  after  several  hours. 
The  resulting  solution,  containing  now  a  biphenylene  triarylmethyl, 
absorbed  oxygen  slowly  with  the  formation  of  the  corresponding  peroxide. 
The  'amount  of  oxygen  absorbed  was  determined  quantitatively  and  was 
found  to  be  practically  1/8  of  the  amount  calculated  for  the  quantity  of  the 
original  free  radical  used.  This  behavior  is  exactly  that  which  would  be  ex- 
pected from  Equation  4,  for  the  amount  of  9-phenyl-3-methoxy-fluoryl  (X). 

TABLE  IV 

OXYGEN  ABSORPTION  BY 
Methyl-triphenylmethyl  Oxygen  Absorbed 

G. 

1.0000 
1.0000 
0.8929 

The  benzene  solution  was  concentrated,  and  upon  addition  of  petroleum  ether  the 
fine  white  crystalline  peroxide  separated,  and  after  several  recrystallizations  from  ben- 
zene and  petroleum  ether  melted  with  decomposition  at  200°,  and  proved  to  be  9- 
phenyl-3-methoxy-fluoryl  peroxide. 

Analyses.     Calc.  for  C4oH3oO4:   C,  83.62;  H,  5.23.     Found:   C,  83.86;  H,  5.24. 

£-Anisyl-biphenylenemethyl  Peroxide  (VI). — £-Anisyl-biphenylene  carbinol  was 
made  according  to  Schlenk  and  Mair,6  by  the  action  of  />-methoxy-phenylmagnesium 
iodide  on  fluorenone.  Although  Schlenk  obtained  this  carbinol  only  as  an  oil,  it  may  be 
crystallized  from  petroleum  ether  as  small  transparent  plates  which  melt  at  87-88°. 

Analyses.     Calc.  for  C20H16O2:   C,  83.33;  H,  5.55.     Found:   C,  83.23;  H,  5.46. 

The  chloride  was  prepared  from  the  carbinol  by  using  acetyl  chloride  rather  than 
hydrogen  chloride.  It  melted  at  149  °,  as  described.  By  the  action  of  molecular  silver, 
the  chloride  was  converted  into  the  corresponding  free  radical,  and  the  latter  on  exposure 

16  Baeyer  and  Villiger,  Ber.,  37,  608  (1904). 


Cc.  (N.  T.  P.) 

Calc.  for  amount  of 
original  rad. 

% 

Calc.  for  amount  of 
compound  V 

% 

13.8 

33.6 

100.8 

13.5 

32.9 

98.7 

13.0 

35.5 

106.5 

20 

to  air  gave  the  peroxide;  this  was  found  to  melt  at  192°,  as  given  by  Schlenk  and  Mair. 
This  peroxide  differed  from  the  peroxide  isolated  in  the  light  experiment  of  our  free 
radical,  in  respect  to  melting  point,  solubility  in  benzene,  and  color  produced  upon  addi- 
tion of  sulfuric  acid. 

9-Phenyl-3-methoxy-fluoryl  (X)  and  the  Peroxide  (XI). — 3-Methoxy-fluorenone 
was  made  from  anthranilic  acid  according  to  Ullmann  and  Bleir,8  and  was  converted 
into  the  carbinol  (IX)  by  the  action  of  phenylmagnesium  bromide.  After  several  re- 
crystallizations  from  benzene  and  petroleum  ether,  the  carbinol  melted  at  84°.  On 
treatment  in  benzene  with  hydrogen  chloride,  it  gave  the  carbinol  chloride;  m.  p.,  119°. 
Analysis.  Calc.  for  CaoHwOCl:  Cl,  11.57.  Found:  11.20. 

The  chloride  when  dissolved  in  bromobenzene,  and  shaken  with  molec- 
ular silver  gave  solutions  of  the  free  radical.  These  were  purple;  the 
color  deepened  markedly  with  slight  increase  of  temperature  and,  with 
decrease,  returned  again  to  its  former  intensity.17  The  combination  with 
oxygen  is  somewhat  slow;  0.3883  g.  of  the  chloride  gave  a  solution  of  the 
radical  which  absorbed. in  several  hours  14.6  cc.  of  oxygen  (N.  T.  P.), 
which  is  equal  to  102.8%  of  the  calculated  amount. 

The  peroxide  was  prepared  by  passing  air  through  a  benzene  solution 
of  the  free  radical.  Upon  addition  of  petroleum  ether  to  the  concentrated 
benzene  solution,  the  peroxide  crystallized.  After  several  recrystalliza- 
tions  it  melted  with  decomposition  at  200°  and  proved  in  every  respect 
identical  with  the  peroxide  obtained  by  the  photochemical  reaction. 

Non-formation  of  Additive  Compounds  by  ^-Methoxy-triphenyl- 
methyl. — The  free  radical  was  crystallized  from  the  following  solvents  in 
order  to  determine  whether  it  formed  additive  compounds :  Ethers :  ethyl 
ether,  butylmethyl  ether,  butylethyl  ether;  Esters:  ethyl  acetate,  propyl 
acetate;  Ketones:  acetone,  methylethyl  ketone,  diethyl  ketone;  Carbon 
disulfide.  Using  the  same  procedure  as  described  under  ^-benzyloxy- 
triphenylmethyl,  it  was  found  that  the  free  radical  formed  no  additive 
compounds,  quite  in  contrast  to  triphenylmethyl. 

Degree  of  Dissociation  of  Di-p-Methoxy-hexaphenylethane. — The 
molecular- weight  determinations  were  made  under  exactly  the  same  condi- 

TABLEV 
MOLECULAR  WEIGHT  OF  DI-PARA-METHOXY-HEXAPHENYLETHANE 

Solvent  Solute  Cone.  Depression  Dissociation 

G.  G.  %  °  C.  Mol.  wt  % 

SOLVENT:  ETHYLENE  CHLOROBROMIDE,  F.  p.,  —17°    #  =  85.4 
25.32 


25.22 


0.2524 

0.99 

0.213 

399.8 

36.6 

0.5417 

2.14 

0.442 

413.4 

32.0 

0.8393 

3.31 

0.669 

433.1 

39.0 

1.1435 

4.51 

0.906 

435.7 

28.2 

0.2588 

1.02 

0.222 

394.7 

38.3 

0.5675 

2.25 

0.465 

413.3 

32.1 

0.8542 

3.39 

0.688 

420.4 

29.8 

1.1296 

4.48 

0.896 

426.9 

27.9 

17  Gomberg  and  Cone,  Ber.,  39,  2968  (1906). 


21 
SOLVENT:  BENZENE,  F.  p.,  4.6 °    K  =  53.0 


20.31 


20.55 


20.07 


20.03 


24.99 


25.41 


24.96 


25.11 


25.06 


25.25 


0.2996            1.47 

0.182 

429.6 

27.1 

0.6596            3.25 

0.386 

445.9 

22.4 

0.9559            4.71 

0.558 

447.0 

22.1 

1.2743            6.27 

0.744 

447.0 

22.1 

0.3220            1.56 

0.189 

439.4 

24.2 

0.5934            2.89 

0.347 

441.0 

23.8 

0.9875            4.51 

0.541 

442.1 

23.5 

1.2363            6.01 

0.721 

442.2 

23.4 

SOLVENT:  NITROBENZENE 

,  F.  p.,  5.8° 

#  =  70.2 

0.2654            1.32 

0.222 

418.2 

30.5 

0.5782            2.88 

0.480 

421  .4 

29.5 

0.9011            4.49 

0.742 

424.8 

28.5 

1.1824            5.89 

0.980 

422.0 

29.4 

0.2942            1.47 

0.246 

419.1 

30.3 

0.5979            2.98 

0.500 

419.1 

30.3 

0.9124            4.55 

0.760 

420.8 

29.7 

1.2084            6.03 

1.010 

419.3 

30.2 

SOLVENT:  ETHYLENE  DIBROMIDE,  F.  p.,  9.8° 

#  =  116.1 

0.2306            0.92 

0.278 

385.4 

41.7 

0.5383            2.15 

0.617 

405.3 

34.7 

0.8216            3.28 

0.936 

407.8 

33.9 

0.2834            1.11 

0.329 

393.6 

38.7 

0.5741            2.26 

0.644 

407.3 

34.0 

0.8961            3.53 

1.004 

407.8 

33.9 

SOLVENT:  /J-BROMOTOLUENE, 

F.  p.,  26.6° 

#  =  84.7 

0.3175            1.27 

0.259 

416.0 

31.2 

0.6343            2.54 

0.516 

417.1 

30.9 

0.9067            3.63 

0.734 

419.2 

30.2 

1.2426            4.98 

1.006 

419.1 

30.3 

0.3032            1.21 

0.246 

415.7 

31.3 

0.5529            2.20 

0.445 

419.1 

30.3 

0.8654            3.44 

0.695 

420.0 

30.0 

1.1944            4.75 

0.961 

419.2 

30.2 

SOLVENT:  P-DICHLOROBENZENE,  F.  p.,  53° 

#  =  73.5 

0.2730            1.09 

0.215 

372.4 

46.6 

0.4969            1.98 

0.375 

388.6 

40.5 

0.7676            3.06 

0.568 

396.4 

37.7 

1.0146            4.05 

0.749 

397.3 

37.4 

0.3223             1.27 

0.243 

386.1 

41.4 

0.6040            2.39 

0.443 

396.9 

37.6 

0.9124            3.61 

0.660 

402.4 

35.7 

1.2134            4.80 

0.864 

408.8 

36.0 

tions  as  described  for  the  benzyloxy  radical.  The  substance  was  crystal- 
lized from  absolute  ether,  and  each  set  of  determinations  represents  a 
separate  preparation.  The  quantity  of  the  free  radical  used  in  these  ex- 
periments (Col.  2)  is  designated  as  the  hexa-aryl  ethane. 


22 

5  Summary 

1.  A  number  of  derivatives  of  p-benzyloxy-  and  ^-methoxy-triphenyl 
carbinol  have  been  synthesized. 

2.  The  2  free  radicals,  £-benzyloxy-  and  ^-methoxy-triphenylmethyl, 
have  been  prepared.     A  study  has  been  made  of  the  important  reactions 
of  these  2  radicals  toward  oxygen,  iodine,  hydrogen  chloride  and  light,  and 
of  their  capacity  to  form  additive  compounds. 

3.  The  degree  of  dissociation  of  the  2  hexa-arylethanes  into  the  corre- 
sponding triarylmethyls  has  been  determined  in  6  solvents  over  a  range  of 
temperature  from  — 17°  to  +53°,  and  in  concentrations  from  1  to  6%. 
The  degree  of  dissociation  was  found  to  be  influenced  by  concentration  of 
the  free  radical,  temperature,  and   the  nature  of  the  solvent.      The  benzyl- 
oxy  compound  dissociates  to  the  extent  of  from  26  to  56%,  the  methoxy, 
to  the  extent  of  from  22  to  42%. 

This  investigation  was  made  with  the  assistance  of  The  National  Aniline 
and  Chemical  Company  Fellowship.  We  wish  to  express  our  obligations 
for  the  generous  aid  we  have  thus  received. 


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